The present invention relates to a control system of an engine, which includes a cylinder and a fuel injector for injecting fuel into the cylinder, and in which a mixture gas of the fuel and air combusts inside the cylinder.
Conventionally, in engines, it has been discussed to improve engine performance by injecting water into the cylinder.
For example, JP4335533B discloses an engine which injects supercritical water into a cylinder before or simultaneously with fuel injection, so as to reduce a combustion temperature inside the cylinder and reduce production of NOR.
Here, in engines, it is desired to improve exhaust emission performance and fuel efficiency. Especially within a high engine speed operating range where an engine speed is high, since mechanical resistance increases and exhaust gas is discharged from an engine while its temperature still remains comparatively high, thermal efficiency is low. Therefore, it is desired to improve thermal efficiency and fuel efficiency within this high engine speed operating range.